diff --git a/gcc/expr.c b/gcc/expr.c
index 00660293f72e5441a6421a280b04c57fca2922b8..7daeb8c91d758edf0b3dc37f6927380b6f3df877 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -2749,7 +2749,7 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src)
 {
   int i, n_regs;
   unsigned HOST_WIDE_INT bitpos, xbitpos, padding_correction = 0, bytes;
-  unsigned int bitsize;
+   unsigned int bitsize = 0;
   rtx *dst_words, dst, x, src_word = NULL_RTX, dst_word = NULL_RTX;
   /* No current ABI uses variable-sized modes to pass a BLKmnode type.  */
   fixed_size_mode mode = as_a <fixed_size_mode> (mode_in);
@@ -2782,7 +2782,7 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src)
 
   n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
   dst_words = XALLOCAVEC (rtx, n_regs);
-  bitsize = BITS_PER_WORD;
+
   if (targetm.slow_unaligned_access (word_mode, TYPE_ALIGN (TREE_TYPE (src))))
     bitsize = MIN (TYPE_ALIGN (TREE_TYPE (src)), BITS_PER_WORD);
 
@@ -2791,6 +2791,17 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src)
        bitpos < bytes * BITS_PER_UNIT;
        bitpos += bitsize, xbitpos += bitsize)
     {
+      /* Find the largest integer mode that can be used to copy all or as
+	 many bits as possible of the structure.  */
+      opt_scalar_int_mode mode_iter;
+      FOR_EACH_MODE_IN_CLASS (mode_iter, MODE_INT)
+      if (GET_MODE_BITSIZE (mode_iter.require ())
+			    <= ((bytes * BITS_PER_UNIT) - bitpos)
+	  && GET_MODE_BITSIZE (mode_iter.require ()) <= BITS_PER_WORD)
+	bitsize = GET_MODE_BITSIZE (mode_iter.require ());
+      else
+	break;
+
       /* We need a new destination pseudo each time xbitpos is
 	 on a word boundary and when xbitpos == padding_correction
 	 (the first time through).  */